EVER since the Cleveland Indians put three infielders to the right of second base in 1948 against Ted Williams, a left-handed batter who rarely hit ground balls the opposite way, baseball teams have deployed defensive shifts against powerful lefties.Williams could easily have bunted the ball towards third base and sauntered down to first for a single. But he continued swinging as hard as he could, arguing that the defence would be irrelevant if he managed to hit a home run.

Since then, the vast majority of hitters who have faced shifts have similarly refused to change their approach. Their opponents have been delighted to watch them pound ground ball after ground ball straight towards the repositioned infielders.

Yet despite their effectiveness, defensive shifts have been a relative rarity for most of modern baseball history. They have almost never been used against right-handed batters: because the first baseman must stay reasonably close to the base to receive a throw, there would be a gaping hole in the defence if all the other infielders were on the other side of the diamond. And even among lefties, only the most extreme pull hitters have faced shifts regularly. When there is even a modest chance that a batter will hit a ball towards third base, managers have tended to play a standard defence.

In recent years the Tampa Bay Rays, baseballs most innovative franchise, have abandoned this orthodoxy and begun shifting much more aggressively. The Rays play in one of baseballs smallest markets and have one of its lowest payrolls. Nonetheless, they have managed to make the playoffs in three of the last four seasons thanks to their savvy management. Rather than simply alternating between one of two infield alignments – normal positioning and a Williams Shift – Tampa Bay has studied where each opposing batter tends to hit the ball and concentrated their infielders in those areas, even against right-handed hitters.

The results have been remarkable. From 2009-11 just 22.4% of the Rays opponents ground balls became hits, compared with 23.6% for an average American League team. That difference may sound small. But it amounts to an advantage of 21 hits per season – which translates into a 1.7-game improvement in the teams won-lost record.

That difference may sound small. But it amounts to an advantage of 21 hits per season – which translates into a 1.7-game improvement in the teams won-lost record.

Signing a player on the free-agent market who would help the club by a similar amount would cost over $8m. There is no way to prove that shifts are the cause of this success – the pitchers might have induced ground balls that are unusually easy to snare, or the infielders might simply be excellent defenders (and at least one of them, Evan Longoria, certainly is). But defensive positioning is by far the most likely explanation for such a big, consistent edge over three separate seasons.

This year, the rest of the league seems to be catching up at last to Tampa Bay. According to John Dewan of Baseball Info Solutions, a data-gathering and analysis company, major-league teams are on pace to deploy twice as many shifts this season as they did in 2011. Unsurprisingly, the share of ground balls that become hits for the league as a whole has dropped from 23.7% last year to 22.6% in 2012. In contrast, the proportion of balls hit in the air that go for hits has fallen by only 0.3 percentage points, an insignificant decline. Although the Rays are still easily the leaders in the tactic – they are projected to put on 695 shifts this season, over three times as many as their average in 2010-11 – they are no longer alone. The runners-up are Baltimore, on pace for 386 shifts, and Cleveland, on track for 342. Neither team was expected to contend this season, but both are currently in first place in their divisions.

There are two potential interpretations of this trend. The pessimistic view is that it shows that small-market franchises are doomed. Before the Rays became successful, the Oakland Athletics used cutting-edge statistics in the early 2000s to compile a winning team on a shoestring budget. Their achievements were recently featured in the hit film Moneyball. However, once richer clubs began using their methods against them, they could no longer compete, and they have not had a winning record since 2006. The same fate might well await Tampa Bay. Eventually, all the market inefficiencies will be ironed out, and the only way for teams to win more games will be to spend more money.

Fortunately, there is a compelling counter-argument to this dystopian vision. Baseball strategy is not a puzzle with a single solution. Instead, it is a dynamic system, in which a tactic that works against one approach can be neutralized by another. And when it comes to shifts, the response is as clear as the sea of empty infield dirt abandoned by the defenders congregating on one side of the diamond. All it takes is a handful of well-placed bunt singles to make the shift a losing strategy for the defence. Carlos Pea of – who else? – the Rays has proven himself a master of this riposte. As a result, he has enjoyed a double boost to his production: he both secures free hits using bunts when he faces a shift, and gets more hits on ground balls to the right side than do other lefty sluggers, since the threat of his bunting means he faces fewer shifts than they do.

Back in the 1940s, Williams managed to be the games best offensive player despite losing dozens of hits to the shift named after him. Today, the game has evolved to a point where stars can no longer afford to be so stubborn. Sluggers who can bunt are the new market inefficiency, and the first team that has its power hitters practicing this wimpy technique will enjoy a crucial edge. For all we know, Tampa Bay may be doing so already.